1. Field of the Industrial Application
The present invention relates to a recording apparatus in a printer for printing information on a thermal paper by using, for example, a thermal head.
2. Prior Art
In a first conventional recording apparatus, there are provided a recording head that is elastically contacted with a platen by a spring, a release lever 1 swingably mounted on a head supporting plate for supporting the recording lever, a connecting member that shifts in cooperation with the swing motion of the release lever, and a release cam drivingly swung in accordance with a shift of the connecting member. By manually swinging the release lever, in the non-used condition, in order to prevent any deformation of the platen, the recording head may be kept away from the platen (Japanese Utility Model Application Laid-Open No. Hei 2-139752).
In a second conventional recording apparatus, a recording head is provided in an interior of a case body, and a platen and a roll holder for receiving and holding a roll of recording paper are openably provided in a front surface of the case body, respectively.
In a third conventional thermal print head, a head base plate having heating dots (recording head) is provided on a base plate, on one hand, a terminal portion of the head base plate is pressed and fixed by a pressing cover, and on the other hand, a positioning piece having engaging grooves engaged with a shaft of the platen are bent and integrally formed (Japanese Patent Examined Publication No. Hei 5-7187).
In such a first conventional apparatus where the release lever is manually swingably driven to separate the recording head from the platen, there are only two conditions where the recording head and the platen are elastically contacted with each other and are separated away from each other. In the condition where the recording head is separated away from the platen, i.e., the recording stand-by condition, it is impossible to feed the recording paper.
Also, in the first conventional apparatus, in order to separate the recording head away from the platen, it is necessary to swingably drive the release lever. For this reason, even if the recording operation is completed, if the user forgets the operation to separate the recording head away from the platen, the condition where the recording head is pressingly contacted with the platen is kept for a long period of time. As a result, there is a high fear that the pressure of the recording head against the platen would cause the platen to be deformed.
In a structure in which the roll holder and the platen are provided on the side of the front cover as in the second conventional apparatus, when the rolls of recording paper are replaced, it is sufficient to open the front cover and to close the front cover after setting the roll of recording paper with its end overlapping over the platen. Thus, the loading operation of the recording paper is simple. However, for example, when the front cover is opened, it is necessary to manually or electrically separate the recording head, located on the side of the case body, away from the platen to thereby eliminate the contact between the recording head and the platen in the opening/closing operation and to protect the platen from a damage caused by the friction. In the case where the apparatus is so constructed as to meet this requirement, a number of components are required and its structure is complicated to increase a cost. Also, in the second conventional apparatus, as in the first conventional apparatus, in the condition where the recording head is separated away from the platen, i.e., the recording stand-by condition, it is impossible to feed the paper.
Also, in the structure where the roll holder and the platen are provided on the side of the front cover as in the second conventional apparatus, the recording paper loading operation is simple but it is necessary to increase a relative positional precision between the recording head and the platen after the front cover has been closed. In order to enhance the relative positional precision between the recording head and the platen, it is necessary to control the component precision of a number of individual components needed for supporting the printing head and the platen and the assembling precision therefor at a high level.
Also, in the second conventional apparatus, in opening the opening/closing member, the recording head and the platen are separated away from each other. Accordingly, the substantial pressure for the recording must be applied when the recording condition is available after the opening/closing member has been closed. In addition, the opening/closing member must be prevented from accidentally opening during the recording operation.
In the apparatus in which the heating dots (recording head) and the engaging grooves engaged with the shaft of the platen are formed on the same member (i.e., base plate) as in the third conventional thermal head, it is possible to exactly position the platen relative to the heating dots and to hold them without any adverse affect on the mounting precision or a degree of true circle of the surface. However, in such a structure, it is impossible to provide the platen on the side of the opening/closing member such as an openable front cover in which the recording head is separated away from the platen. As a result, the operation such as replacement of the recording paper rolls becomes extremely complicated, and the loading operation of the recording paper is extremely troublesome.